But Johnson ended up with no silver car and no money after being stung by a fake online ad. Con artists pretended to be connected to a bank repo business but really touted fake car deals as a way to rake in cash.

Car troubles — including misrepresentations in ads, faulty repairs and scams involving used car sales — are among the top complaints made to state and local consumer protection agencies, according to a survey by the Consumer Federation of America and the North American Consumer Protection Investigators.

The used car complaints vary. The consumer survey pointed out one report of a worthless trade-in promotion in Maryland that promised 100% of the original manufacturer's suggested retail price as a trade-in allowance. But tricky fine print meant that one consumer received no cash on a trade-in for a 2000 Buick LeSabre.

The complaints about online ads relating to used cars, though, can be far broader in scope, as con artists have netted more than $50 million in the past four years.

Based on data provided by the FBI, the Internet Crime Complaint Center has received 1,685 auto-auction fraud complaints with a reported loss of $4.9 million this year through July 31. In all of 2011, the Internet Crime Complaint Center received 4,066 auto-auction fraud complaints with $8.3 million in reported losses.

The Better Business Bureau for eastern Michigan is warning consumers about criminals who hijack online ads to "sell" vehicles that they do not own and have no intention of delivering.

Name: Susan Tompor

Title: Your Money columnist

Often, a good-looking car is advertised at an amazing price. The BBB notes that some type of "buyer protection plan" can be offered, but it's a scam, too.

Jack Christin Jr., associate general counsel for eBay Motors in San Jose, said consumers should watch for any used car sale that starts on Craigslist or elsewhere — but then the seller supposedly moves the transaction to another website, such as eBay Motors.

Christin stressed that a hard-luck story — a sick child or a lost job or a divorce — is used to hook potential buyers into believing that the low price is engineered for a quick sale.

Scammers don't often offer a $10,000 minivan for $800. Usually, the sales price is a deep discount but a bit more believable. "It's not like so good that it seems bizarre," Christin said.

Given the Internet, it's easy to show photos of a car online or via e-mail that you don't own.

But Christin says it's also possible to buy a car sight unseen in a legitimate online car deal. He noted that eBay Motors has sold more than 4.5 million cars online since 2000.

Buying a car out of state — and not seeing it until delivery — is not necessarily a problem, if the deal is being conducted in a legitimate way, Christin said. Many times legitimate buyers and sellers live in different states and work out a delivery plan.

VIDEO: USA TODAY consumer columnist Jayne O'Donnell offers tips on how to watch out for previously wrecked used cars.

What buyers don't want to do is pay a stranger for a used car or any item via Western Union or MoneyGram. Even putting that money on a store-bought prepaid card could be a great way to lose cash, if you don't know the seller.

Christin has been pleased to see some consumers are becoming more cautious after efforts to get out the word. He's seen consumers jump into online conversations on car-enthusiast websites to warn others who mentioned that they just saw a fantastic deal on a great car — but maybe that deal seemed somewhat odd.

Johnson cannot remember how he found that low-mileage 2004 Jag. Now, he understands the red flags that didn't bother him back when he was buying the car in February 2011.

The seller in his case was never around to talk on the phone. Every conversation was online. Free shipping seemed a little odd, too, in retrospect. His money was wired from his bank to, ultimately, an overseas bank account.

The FBI, he said, told him: "I'm sorry to tell you your money is gone."

Johnson tries to be philosophical, saying that his wife reminds him that he cannot do anything about the money. It's gone.

•One sign of a scam: The con artist in a used-car scam may refuse to meet the buyer in person or even allow a vehicle inspection — claiming they're moving soon or they need to rush the sale.

•Don't get caught up in a long sob story.

•Do not use a money transfer service, such as Western Union, to pay a stranger for a used car or other item. Such services are convenient but best used to send money to people you know. See www.westernunion.com/stopfraud.

•Be careful if you get an e-mail saying you won a top bid for an auction for a used car. It's best to go back to the online auto-auction site to double-check. Con artists can capture e-mail addresses and contact you directly about cars being sold by someone else.

•The FBI's Internet Crime Complaint Center is at www.ic3.gov.

•Think twice about dealing with someone in another country.

•Beware if you are asked to pay by loading cash onto a store-bought prepaid card. Consumer agencies say the cards are an easy way for scammers to get cash and not get caught.

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